Question: A baker has $5\dfrac14$ pies in her shop. She cut the pies in pieces that are each $\dfrac18$ of a whole pie. How many pieces of pie does she have?
Explanation: We can think about this problem like this: $ {\text{number of slices}} = {\text{all the pie}} \div {\text{size of each slice}}$ ${\text{?}} = {5\dfrac14 \text{pies}} \div {\dfrac{1}{8} \text{pie}}$ $\phantom{?} = {\dfrac{21}{4} \text{pies}} \div {\dfrac{1}{8} \text{pie}} ~~~~~~~{\text{Rewrite } {5\dfrac14} \text{ as } { \dfrac{21}{4}}}$ $\phantom{?} = {\dfrac{21}{4}} \times \dfrac{8}{1} ~~~~~~~{\text{Rewrite dividing by} {\dfrac{1}{8}} \text{ as multiplying by} \dfrac{8}{1}}$ $\phantom{?} =\dfrac{21 \times 8}{4 \times 1}$ $\phantom{?} =\dfrac{168}{4}$ $\phantom{?} = {42 \text{ slices}}$ She has 42 slices.